It is currently believed that future military airborne and shipboard communication systems will employ the Joint Tactical Radio System (JTRS), which comprises a family of affordable, high-capacity tactical radios to provide both line-of-sight and beyond line-of-sight Channel 4 International (C4I) capabilities. The radios are expected to cover an operating spectrum of about 2 to 2000 megahertz (MHz), and will be capable of transmitting voice, video, and data communications.
In the anticipated configuration, an aircraft or ship will comprise transmitting and receiving antennas that will transmit and receive radio communications. One example arrangement is depicted in FIG. 1. More particularly, FIG. 1 illustrates a portion of a fiber optic/radio frequency communication system 10 comprising a radio frequency (RF) receiver 12 and an RF transmitter 14. Connected to the RF receiver 12 is a fiber optic (FO) transmitter 16, which is in optical communication with a fiber optic receiver 18 via fiber optic line 20. With such apparatus, RF signals can be received with the RF receiver 12, provided to the FO transmitter 16, and then transmitted to the FO receiver 18 via the fiber optic line 20, which may reside within a control center of the aircraft or ship. In the system 10 of FIG. 1, the FO transmitter 16 and FO receiver 18 are distinct components to permit physical separation.
Often times, the antennas (not shown) of the RF receiver 12 and the RF transmitter 14 are co-located. Even when this is not the case, the antennas may not be physically separated by a great distance. In such cases, strong interfering signals from the transmitting antenna may be received by the receiving antenna and, therefore, may be output by the RF receiver to the fiber optic transmitter and the remainder of the optical portion of the communication system. Given that the transmitted signals are often much stronger than the received signals, it is possible for the received signals to become lost in the data transmitted along the optical portion of the communication system. In other words, the transmitted signal acts as an interfering signal (SI) that can cause reduction of the carrier-to-noise density (C/NO) in the received, or desired, signal (SD). Accordingly, needed is a communications systems similar to that depicted in FIG. 1, in which the interfering signal can be attenuated to enable detection of the desired signal, SD.